The Illinois land cover dataset from the early 1800s, credited to the Illinois Natural History Survey (INHS), uses historical land survey records like the Public Land Survey System (PLSS) to recreate the pre-settlement environment of Illinois. This data aids ecological restoration, historical comparison, and understanding landscape changes due to agriculture and urbanization. It is used by scientists, land managers, and educators for conservation and environmental planning. Formatted as GIS-compatible shapefiles or raster datasets, it maps and analyzes spatial patterns of historical land cover. The dataset includes geographic units such as township-range sections, dominant vegetation types, estimated extent, and surveyor notes. Although useful for spatial analysis, it may oversimplify local variations in land cover. Data cleaning involved resolving inconsistent terminology and correcting biases, but assumptions made during vegetation classification and boundary definitions introduced uncertainty. The creators’ focus on native vegetation enhances ecological accuracy while potentially excluding other perspectives. This dataset is valuable for environmental research but requires careful application to avoid misleading conclusions.